In sewing machines it is desirable in some sewing situations to be able to use more than one needle as in the case, for example, of multicolored embroidery stitching. When substituting two or more needles for a single needle in a zig-zag machine, it becomes necessary to limit the swing amplitude of the needles, or the bight stops, as the two or more needles would swing in a wider path than a single needle which could take the needles out of the area covered by the aperture in the needle plate resulting in a breaking of the needles during penetration of the fabric. It is known to limit the bight stops in mechanically controlled zig-zag machines when substituting multiple needles for single needles, such as for example shown in U.S. Pat. No. 3,296,987 granted Jan. 10, 1967. In such mechanically controlled machines the zig-zag motion is generally imparted to the needle bar by a cam mechanism which is connected to the needle bar mechanism through a cam follower and associated linkage. In order to adjust or limit the bight stops in such machines means are generally provided for altering the linkage between the cam mechanism and the needle bar mechanism.
In electronically controlled sewing machines of the type disclosed in co-pending U.S. patent application Ser. No. 431,649 filed on Jan. 8, 1974, cam mechanisms of the type mentioned above are completely eliminated and logic means are used to select and release stitch information stored in a memory means in timed relation with the operation of the sewing machine. Digital information from the memory means is converted to positional analog signals which control closed loop servo means including moving coil linear actuators directly controlling the position of conventional stitch forming instrumentalities such as the zig-zag mechanism for the needle bar. Therefore, it will be seen that in machines of this type, means other than those which have been provided heretofore must be used for limiting the bight stops. What is required in order to limit the bight stops in an electronically controlled machine is means for limiting the positional analog signals which control the closed loop servo means to thereby provide a signal to said servo means which is reduced in proportion to the reduction in swing amplitude or bight required for the situation wherein multiple needles or the like are used.